Estudo da oximação de propanal e de sua determinação por meio de entalpimetria

AUTOR(ES)
DATA DE PUBLICAÇÃO

1985

RESUMO

In this work, the study of the oximation reaction with propanal, by mean of calorimetry was undertaken. Special enphasis was given to the effects of acidity in the various steps of the reaction, and the reaction rate was determined in the pH range from 0.5 to 10.5. It was found that the profile of the curve for the observed rate constant vs pH presented a bell shape with maximum at pH 2.6. It was also found that the magnitude of the temperature change was influenced by the acidity of the medium, giving a fast rise in the beginning, followed by a more slow variation afterword. The results obtained in this study were interpreted as indicative of a two-steps reaction, including the formation of an intermediate compound and its dehydration. On the basis of the results for the effects of the acidity in the reaction, a method for the determination of propanal was developed, by mean of direct injection enthalpimetry. The proposed procedure is fast, is based on the reaction of propanal with hydroxylamine hydrochloride, and uses simple equipment of easy construction. The results for the determination of 10 samples of propanal gave a precision around 1.4%.

ASSUNTO(S)

dinamica dos gases entalpia alcool propilico - analise termica

ACESSO AO ARTIGO

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